This application claims the priority of Korean Patent Application No. 2003-74914, filed on Oct. 25, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a middle ear implant transducer of a hearing aid.
2. Description of the Related Art
A middle ear implant transducer of a hearing aid, which is a core part of an artificial middle ear, is directly implanted into the ossicular chain in a middle ear of a patient having a hearing disorder by surgery and is extensively used to remedy extreme conductive hearing loss, sensorineural hearing loss, or mixed hearing loss.
A transducer can prevent noise caused by an external magnetic field with excellent efficiency. A transducer includes two identical tubular permanent magnets in the center of a tubular coil such that the same poles of the permanent magnets face each other. The permanent magnets and the coil are connected by a vibrating member. A conventional transducer is disclosed in Korea Pat. No. 10-2003-74914 and U.S. Pat. No. 6,735,318 submitted by the current applicant. The permanent magnets vibrate in response to variations in a magnet flux generated by the coil, and the vibration of the permanent magnets is transmitted to the transducer via the vibrating member causing the transducer to vibrate. Since such a middle ear implant transducer directly transmits vibrations corresponding to a sound signal to the middle ear, distortion is small, and hauling due to sound feedback is also small.
Despite the above advantages, a possibility of generating distortion when vibration characteristics of the transducer are different from those of the middle ear exists. In particular, when a resonance frequency or a vibration displacement of the vibration characteristics of the transducer is different from that of the middle ear, severe distortion may be generated.